Corrosion-resistant alloys



Patented Jan. 31, 19238.

UNITED s'rarss PATENT orrica.

MICHAEL G. GORSON, 0F JACKSON HEIGHTS, NEW YORK, ASSIGNOB TO ELECTEDMETALLURGICAL COMPANY, A CORPORATION OF WEfiT VIRGINIA.

GORROSION--RESISTANT ALLOYS.

IN 0 Drawing.

The invention relates to copper-manganese alloys and comprises a groupof compositions of this class which are highly resistant to attack bycorrosive agents, such for example as the inorganic acids.

I have discovered that the property 0' corrosion-resistance is developedto a remarkable degree in copperenanganese alloys when the manganesecontent is between 35% and 55%. Alloys of these two metals containing upto of manganese have been used industrially, and other alloys of theseries with higher manganese have been prepared in the laboratory; butthe former alloys show little resistance tocorrosion and it has not beenobserved that any alloys ofthe latter group were superior in. thisrespect.

The ability of the alloys of the invention to resist corrosion isapparently due to the relationship between the manganese and coppercontents, and there are several other elements which may be present inmoderate amounts without important effect on the properties of thealloy. Among these there may be mentioned tin, zinc, nickel and iron.The manganese used in making the alloy may be the product of reductionby carbon, silicon, or aluminum. If carbon-reduced metal carrying morethan about 0.5% of carbon is used, the final alloy is unable to dissolvethe whole of the carbon thus introduced. Usually about 0.2% to 0.3% ofcarbon will. be found in the finished alloy under these conditions, andany excess carbon will eliminate itself by rising to the surface of themelt. Silicon, if present in too great quantity, is somewhat detrimentalto the corrosion-resistance of the alloy and injures its workingproperties to a great extent riluminother mic manganese is quitesuitable for the manufacture of said alloys.

The binary copper-manganese alloys containing to of manganese appear tobe solid solutions, at least when they are quenched from 850 0. Alloysmade in practicing the invention will usually not be strictly binary incharacter as other elements will be intentionally added or will beintroduced through the use of the impure commercial grades of rawmaterials. Measures should then be adopted to insure homogeneity in thealloy.

19%6. Serial No. 101,813.

prejudicial. to resistance to corrosion. After the annealing the alloymay be cooled slowly orquenched, the latter procedure being pre erablein that it tends'to insure homogeneity in the alloy.

The following figures illustrate the mechanical properties attainablewith alloys according to the invention:

Annealed at Gold rolled, 75% reduction. Tensile strength 125,000lb./in.85,000 .lin. Yield point 65,000 25,000 ElongationinZinches 3% 60%.

The composition preferred for most purposes 1s one containing about 42%of mare ganese.

I claim:

1. An article of manufacture adapted to resist corrosion by inorganicacids, composed of an alloy containing 35% to 55%manganese with thebalance principally copper.

2. An article of manufacture adapted to resist corrosion by inorganicacids, composed of an alloy containing about 452% of manganese with thebalance principally copper.

3. Process of preparing articles resistant to corrosion which comprisesforming the article from a copper-manganese alloy containing 35% to 55%manganese andannealing the article at a temperature above 7 50 C.

r a. Process of preparing articles resistant to corrosion whichcomprises forming the article from a copper-manganese alloy containing35% to 55% manganese, annealing the article at a temperature above 7 500., and then quenching.

In testimony whereof, I my signature.

hHCI-LAEL GLCOBSONi

